Bumped grunt-yui-compressor to 0.4.0 (closes snowplow#424)

Author: fblundun

package.json

@@ -11,7 +11,7 @@
     "grunt-contrib-concat": "~0.3.0",
     "grunt-lodash": "~0.3.0",
     "grunt-s3": "~0.2.0-alpha.3",
-    "grunt-yui-compressor": "git://github.com/snowplow/grunt-yui-compressor.git#feature/issue-8",
+    "grunt-yui-compressor": "git://github.com/snowplow/grunt-yui-compressor.git#0.4.0",
     "intern": "~1.5.0",
     "jstimezonedetect": "~1.0.5",
     "lodash": "^3.1.0",